Modification of alkyd resins with metaor para-hydroxy benzoic acids



United States Patent 2,993,873 MODIFICATION OF ALKYD RESINS WITH META.-

OR PARA-HYDROXY BENZOIC ACIDS Raymond L. Heinrich, Baytowu, Tex., and David A. Berry and Richard J. Dick, Columbus, Ohio, assignors, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N.J., a corporation of Delaware No Drawing. Filed Aug. 28, 1958, Ser. No. 757,662 12 Claims. (Cl. 260-22) This invention relates to modified alkyd resins. More particularly, this invention relates to modified alkyd resins of improved hardness and drying characteristics.

Alkyd resins are widely used in the preparation of surface coating compositions. A particularly desired class of alkyd resins are the so-called oil-modified alkyd resins employed in coatings and prepared by the intercondensation of a polybasic acid (preferably dibasic), a polyol, and an unsaturated fatty acid.

The present invention is directed to a discovery in the field of oil-modified alkyd resins which not only permits the inclusion of mor p-hydroxy benzoic acid acid as a raw material but which also provides oil-modified alkyd resins of improved physical and chemical properties.

It has now been discovered that alkyd resin compositions of improved physical properties may be obtained by replacing from about 20 to about 80 mol percent of the fatty acid component of the alkyd resin with a monocarboxylic aromatic acid component which contains, correspondingly, from about 100 to 10 mol percent of m-hydroxy benzoic acid, p-hydroxy benzoic acid or a mixture thereof. In particular, the alkyd resin coating compositions of the present invention are characterized by rapid drying times and the films prepared therefrom are characterized by excellent flexibility, chemical resistance, and hardness.

Alkyd resin chemistry is well known to those skilled in the art and, in the interest of brevity, will not be discussed in detail. The preparation and physical properties of alkyd resins are described in numerous texts, such as vol. I of Organic Coating Technology, Henry Fleming Payne, John Wiley and Sons, Inc., N.Y., 1954.

Although a wide variety of polybasic acids such as phthalic anhydride, iscphthalic acid, succinic acid, 2.2.1- bicyclo endomethylene-7-heptene-2,B-dicarboxylic acid, etc., may be utilized, the preferred acid is generally phthalic anhydride. Similarly, although a wide variety of polyols such as glycerol, trimethylol propane, pentaerythritol, sorbitol, mannitol, etc. may be utilized, the preferred polyol is generaily glycerol. The polyol should contain an average of from about 2.5 to about 4.5 hydroxyl groups per molecule and, preferably, about 3 hydroxyl groups per molecule.

A wide variety of unsaturated fatty acids may be utilized in the preparation of modified alkyd resins, the source of the fatty acid normally being a naturally occurring vegetable or marine oil such as linseed oil, soybean oil, tall oil, menhaden oil, tung oil, castor oil, etc.

Frequently, minor amounts of additional components such as maleic anhydride, dimerized or bodied fatty acids, saturated fatty acids, etc. will also be utilized.

In general, the polybasic acid, polyol, and fatty acid are interreacted in proportions suflicient to provide about a 5 to 25 weight percent excess of polyol. Excess polyol may be defined as that amount of polyol in excess of the amount necessary to combine with the sum of the acid groups in the fatty acid and the polybasic acid on a theoretical basis. Alkyd resins are conventionally characterized as short oil modified alkyd resins, medium oil alkyd resins, and long oil alkyd resins, depending upon the ratio of fatty acid to the dibasic acid in the prepara- 2,993,873 Patented July 25, 1961 tion of the resin. Long oil alkyd resins are normally prepared by the interreaction of about 3.1 to about 3.4 mol equivalents of polyol with about 2 mol equivalents of polycarboxylic acid and 1 mol equivalent of unsaturated fatty acid. Progressively larger amounts of polycarboxylic acid and progressively smaller amounts of unsaturated fatty acid are utilized to provide for a shorter oil length. Thus, short oil alkyd resins may be prepared by the intercondensation of about 3.1 to about 3.4 mol equivalents of polyol with about 2.3 to about 2.5 mol equivalents of polycarboxyl-ic acid and from about 0.7 to about 0.5 mol equivalent of unsaturated fatty acid.

Accordingly, the alkyd resin compositions of the present invention may be defined as intercondensation products of about 3.1 to about 3.4 mol equivalents of a polyol containing about 2.5 to 4.5 hydroxyl groups per molecule with about 2 to 2.5 mol equivalents of a polycarboxylic acid and about 1 to about 0.5 mol equivalent of a modifier consisting of about 20 to mol percent of an unsaturated fatty acid and, correspondingly, from about 80 to 20 mol percent of'a monocarboxylic aromatic acid component containing, correspondingly, from about to about 10 mol percent of an acid selected from the group consisting of m-hydroxy benzoic acid, p-hydroxy benzoic acid and mixtures thereof. Thus, improved short oil, medium oil and long oil alkyd resins are provided in accordance with the present invention. The improvement is most pronounced with long oil alkyd resins.

When the aromatic monocarboxylic acid component contains less than 100 percent of the hydroxy benzoic acid, the remainder of the component may be an unsubstituted or substituted aromatic monocarboxylic acid such as benzoic acid, orthotoluic acid, para-toluic acid, meta-toluic acid, para-isopropyl benzoic acid, para-tertiary butyl benzoic acid, 2.5-dimethyl benzoic acid, etc. or a suitable mixture of two or more such acids.

The invention will be further illustrated by the following specific examples which are given by way of illustration and not as limitations on the scope of this invention.

EXAMPLE I A plurality of alkyd resins were prepared, utilizing phthalic anhydride, glycerol, an unsaturated fatty acid and, except for the base resin, an aromatic monocarboxylic acid. In preparing the base resin, about 60 weight percent of fatty acid was utilized. The amount of fatty acid utilized in preparing the other resins was less, the amount used being determined by the extent to which the fatty acid Was replaced, on a molar basis, by the aromatic monocarboxylic acid. A 6.7 percent molar excess of glycerol was used in order to obtain equivalent degrees of polymerization.

All of the ingredients were charged at once to a flask fitted with a reflux condenser connected to a Dean-Stark tube. The charge was heated to a temperature of about 450 F. over a 3 to 4 hour period and maintained at this temperature for about 5 to 3 hours. An atmosphere of refluxing xylene vapor was maintained over the cook and vigorous agitation was employed. The final acid number was within the range of about 6.5 to 8.5. Water was azeotropically removed as evolved during the course of the reaction.

In Table I there is listed the aromatic monocarboxylic acid modifiers employed, the extent to which the fatty acid was replaced with the acid modifier on a mol percent basis, and the weight percent of acid modifier utilized, based upon the total charge. In addition, the drying time of the alkyd resins prepared in the above-described fashion is given, together with the hardness of films prepared by drying of the alkyd resin compositions. The drier concentration employed for the air drying tests was about 0.5 weight percent of lead and about 0.05 weight percent of cobalt, based on the weight of the resin solids, and was added to the alkyd resin as a solution of cobalt and lead naphthenate. For the baked film tests, the cobalt salt was employed in an amount sutlicient to provide 0.02 weight percent cobalt.

to about 0.5 mol equivalent of a modifier component consisting of about 20 to 80 mol percent of an unsaturated glyceride oil fatty acids portion and, correspondingly, about 80 to about 20 mol percent of an aromatic monocarboxylic acid ingredient selected from the group consisting of m-hydroxy benzoic acid, p-hydroxy benzoic acid and mixtures thereof.

Table I HYDROXYBENZOIC ACIDS AS MODIFIERS IN PHTHALIC ANHYDRIDE-SOYA-GLYOERIN ALKYDS 1 Modifier Acid None o-Hydroxy m-Hydroxy Beuzoic p-Hydroxy Benzoic Benzoic Mol percent Replacement of Fatty ei 40 60 40 50 60 40 50 60 Wt. Percent Modifier r. 0 13.1 20. 9 3.0 6. 2 13. 1 16.9 20. 9 Dry Time, Tack Free, Hours 100 22 5. 5 5.0 3% 1% 1 1.5 1. 0 1.0 Sward Hardness: 7

Bake 10 16 22 10 16 2A 50 44 52 Air Dry, 28 Days .r 2 18 22 12 16 23 34 36 2 30 2 36 2 44 Flexibility Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Chemical Resistance:

Bake Poor Good Good Good Good Good Good Good Good Good Good Air Dry Poor Good Good Good Good Good Good Good Good Good Good 1 Approximately 62 percent oil length. 2 Air dry, 14 days.

From Table I it will be seen that substantially improved results were obtained through the use of mand p-hydroxy benzoic acid. Note, however, that the results obtained with p-hydroxy benzoic acid were far superior to those obtained with m-hydroxy benzoic acid.

Having thus described our invention, what is claimed is:

1. An alkyd resin composition comprising the intercondensation product of about 3.1 to about 3.4 mol equivalents of a polyol containing an average of from about 2.5 to 4.5 hydroxyl groups per molecule with from about 2 to 2.5 mol equivalents of a polycarboxylic acid and, correspondingly, from about 1 to about 0.5 mol equivalent of a modifier component consisting of about 20 to 80 mol percent of an unsaturated glyceride oil fatty acids portion and, correspondingly, about 80 to 20 mol percent of an aromatic monocarboxylic acid portion containing, correspondingly, from about 100 to about 10 mol percent of an acid selected from the group consisting of m-hydroxy benzoic acid, p-hydroxy benzoic acid, and mixtures thereof.

2. An alkyd resin composition as in claim 1 wherein the polyol is glycerol and the polycarboxylic acid is a phthalic acid.

3. An alkyd resin composition as in claim 1 wherein the polyol is glycerol, the polycarboxylic acid is a phthalic acid, and the fatty acids are soya fatty acids.

4. An alkyd resin composition as in claim 1 wherein the said aromatic mono-carboxylic acid is m-hydroxy benzoic acid.

5. An alkyd resin composition as in claim 1 where' the said aromatic mono-carboxylic acid is p-hydroxy benzoic acid.

6. An alkyd composition comprising the intercondensation product of about 3.1 to about 3.4 mol equivalents glycerol with from about 2 to 2.5 mol equivalents of phthalic anhydride and, correspondingly, from about 1 7. An alkyd resin composition as in claim 6 wherein the unsaturated fatty acids are soya fatty acids and the aromatic acid is m-hydroxy benzoic acid.

8. An alkyd resin composition as in claim 6 wherein the unsaturated fatty acids are soya fatty acids and the aromatic acid is p-hydroxy benzoic acid.

9. An alkyd resin composition comprising the intercondensation product of about 3.1 to about 3.4 mol equivalents of glycerol with about 2 mol equivalents of phthalic anhydride and about 1 mol equivalent of a modifier component consisting of about 40 to mol percent of an unsaturated glyceride oil fatty acids portion and, correspondingly, about 60 to 40 mol percent of para-hydroxy benzoic acid.

10. A11 alkyd resin composition as in claim 9 wherein the unsaturated fatty acids are soya fatty acids.

11. An alkyd resin composition comprising the intercondensation product of about 3.1 to about 3.4 mol equivalents of glycerol with about 2 mol equivalents of phthalic anhydride and about 1 mol equivalent of a modifier component consisting of about 50 to 60 mol percent of an unsaturated glyceride oil fatty acids portion and, correspondingly, about 50 to 40 mol percent of metahydroxy benzoic acid.

12. An alkyd resin composition as in claim 11 wherein the unsaturated fatty acids are soya fatty acids.

References Cited in the file of this patent UNITED STATES PATENTS 2,087,852 Ellis July 20, 1937 2,606,161 Marling Aug. 5, 1952 2,618,616 Tess et a1. Nov. 18, 1952 2,915,488 Kraft et al Dec. 11, 1959 

1. AN ALKYD RESIN COMPOSITION COMPRISING THE INTERCONDENSATION PRODUCT OF ABOUT 3.1 TO ABOUT 3.4 MOL EQUIVALENTS OF A POLYOL CONTAINING AN AVERAGE OF FROM ABOUT 2.5 TO 4.5 HYDROXYL GROUPS PER MOLECULE WITH FROM ABOUT 2 TO 2.5 MOL EQUIVALENTS OF A POLYCARBOXYLIC ACID AND, CORRESPONDINGLY, FROM ABOUT 1 TO ABOUT 0.5 MOL EQUIVALENT OF A MODIFIER COMPONENT CONSISTING OF ABOUT 20 TO 80 MOL PERCENT OF AN UNSATURATED GLYCERIDE OIL FATTY ACIDS PORTION AND, CORRESPONDINGLY, ABOUT 80 TO 20 MOL PERCENT OF AN AROMATIC MONOCARBOXYLIC ACID PORTION CONTAINING, CORRESPONDINGLY, FROM ABOUT 100 TO ABOUT 10 MOL PERCENT OF AN ACID SELECTED FROM THE GROUP CONSISTING OF M-HYDROXY BENZOIC ACID, P-HYDROXY BENZOIC ACID, AND MIXTURES THEREOF. 